Generally described, a gas turbine engine includes a combustor to ignite a mixture of fuel and air so as to produce combustion gases to drive a turbine. The combustor may include a number of fuel nozzles and a pressurized combustion zone surrounded by a liner, a flow sleeve, and an outer casing. The liner and the flow sleeve may define a cooling flow path therebetween. During operation, high pressure air may be discharged from a compressor or elsewhere into the combustor. A portion of the air may be mixed with fuel and ignited within the combustion chamber as described above. A further portion of the air may be channeled through the flow path for cooling the liner and other components. This process may be repeated by any number of combustors positioned in a circumferential array.
Given the multiple uses of the high pressure air, packaging concerns may arise with respect to the end cover and the piping needed for cooling, sealing, and fuel delivery. For example, a portion of the high pressure airflow may be routed to a fuel nozzle pilot system. Pilot flame stability may improve outer nozzle blow off characteristics and also may improve turndown by keeping the outer fuel nozzles attached and more completely burning out carbon monoxide and the like. Due to these packaging constraints, however, the amount of the airflow to the pilot system may be reduced and hence may negatively impact the performance of the pilot system and the overall gas turbine engine.
There is thus a desire for an improved combustor casing manifold such as a pilot manifold system for high pressure air delivery to the end cover and elsewhere so as to reduce packaging concerns. Such a combustor casing manifold may deliver the high pressure air to, for example, a fuel nozzle pilot manifold system while avoiding further intrusions into the end cover and related locations.